Time Frequency Analysis!

Wed Feb 21 13:39:33 CET 2007

Hi Muthu,

Please put cfg.pad at 30.
As you can read in the frequency analysis tutorials, the cfg.pad is used to
pad out your data with zeros until the specified length, to obtain the
spectral interpolation required. I suspect that having your cfg.pad at only
2, while having a data length which is way longer, you run into problems.

JM

-----Original Message-----
From: FieldTrip discussion list [mailto:FIELDTRIP at NIC.SURFNET.NL] On Behalf
Of Muthuraman Muthuraman
Sent: Wednesday, February 21, 2007 1:15 PM
To: FIELDTRIP at NIC.SURFNET.NL
Subject: Re: [FIELDTRIP] Time Frequency Analysis!

Hello JM,

The time axis in my data which i define from 0 to 30 secs

data1.time{1,1}=0:0.0375:29.99875;

after making the changes it works now but i get the only values from

0.125 to 0.625 and all the other values are Nan's

thanking you

with regards
M.Muthuraman.

>From: Jan Mathijs Schoffelen <Jan.Schoffelen at FCDONDERS.RU.NL>
>Reply-To: FieldTrip discussion list <FIELDTRIP at NIC.SURFNET.NL>
>To: FIELDTRIP at NIC.SURFNET.NL
>Subject: Re: [FIELDTRIP] Time Frequency Analysis!
>Date: Wed, 21 Feb 2007 12:41:24 +0100
>
>What's the time-axis in your data?
>
>JM
>
>-----Original Message-----
>From: FieldTrip discussion list [mailto:FIELDTRIP at NIC.SURFNET.NL] On Behalf
>Of Muthuraman Muthuraman
>Sent: Wednesday, February 21, 2007 12:16 PM
>To: FIELDTRIP at NIC.SURFNET.NL
>Subject: Re: [FIELDTRIP] Time Frequency Analysis!
>
>Hello,
>
>A brief on how to do i get the data1, I have the data for 24000 data points
>with 800 Hz sampling rate (30 secs of data), i construct my own data format
>according to the data format specified in fieltrip with
>data.label,fsample,trial,time.
>I tried the way you have mentioned with the window length
>this is what i do
>
>cfg=[];
>winlen=0.5;
>halfwin=winlen/2;
>nwin=2.*(30./winlen)-1;
>cfg.output='pow';
>cfg.method='mtmconvol';
>cfg.channel    = channelselection({'all' 'all'}, data1.label);
>cfg.foi=2:1:30;
>cfg.t_ftimwin=zeros(1,nwin).*winlen;
>cfg.toi=[0:halfwin:30-winlen];
>cfg.taper='hanning';
>cfg.pad=2;
>cfg.keeptrials='no';
>TFRmult=freqanalysis(cfg,data1);
>
>and it throws a error
>??? Subscript indices must either be real positive integers or logicals.
>
>Error in ==> freqanalysis_mtmconvol at 424
>           autspctrmacttap(sgnlop,:) = dum(acttimboi);
>
>Error in ==> freqanalysis at 167
>[freq] = feval(sprintf('freqanalysis_%s',lower(cfg.method)), cfg, data);
>
>Please let me know, why do i get this error
>
>
>Thanking you
>
>with regards
>M.Muthuraman.
>
> >From: Christian Hesse <c.hesse at FCDONDERS.RU.NL>
> >Reply-To: FieldTrip discussion list <FIELDTRIP at NIC.SURFNET.NL>
> >To: FIELDTRIP at NIC.SURFNET.NL
> >Subject: Re: [FIELDTRIP] Time Frequency Analysis!
> >Date: Mon, 19 Feb 2007 13:12:03 +0100
> >
> >Hi Muthuraman,
> >
> >ok, in that case you can try the following (this assumes you have
>windows
> >of length "winlen" which overlap by "halfwin = winlen/2")
> >
> >winlen = 0.5;
> >% this is in seconds you can also use another time window
> >halfwin = winlen/2;
> >
> >% the total number of windows covering the 30 second period
> >nwin = 2.*(30./winlen) - 1;
> >
> >cfg.method = 'mtmconvol';
> >cfg.output = 'pow';
> >cfg.t_ftimwin = ones(1,nwin).*winlen;
> >cfg.toi = [0:halfwin:30-winlen];
> >
> >The important things here to check are
> >1) that cfg.t_ftimwin and cfg.toi contain the same number of elements
> >2) the times you specify in cfg.toi actually correspond to your time
>axis
> >(i.e. do not start before or go on after).
> >
> >If you want to use a different overlap, you need to calculate nwin
> >slightly differently.
> >
> >Hope this helps more,
> >Christian
> >
> >
> >
> >>Thanks for the suggestion but using the mtmfft which i have done
>already
> >>and it works, my interest now is that i would like to use  the Time
> >>frequency analysis 'mtmconvol'  to estimate the power in  the time
> >>frequency scale, in which how to get the whole 30secs  continous  data
>in
> >>one time frequency plot(TFR).
> >>
> >>Thanking you
> >>
> >>with regards
> >>M.Muthuraman.
> >>
> >>>From: Christian Hesse <c.hesse at FCDONDERS.RU.NL>
> >>>Reply-To: FieldTrip discussion list <FIELDTRIP at NIC.SURFNET.NL>
> >>>To: FIELDTRIP at NIC.SURFNET.NL
> >>>Subject: Re: [FIELDTRIP] Time Frequency Analysis!
> >>>Date: Mon, 19 Feb 2007 11:56:19 +0100
> >>>
> >>>Hi Muthuraman,
> >>>
> >>>>One more question regarding the Time frequency Analysis, i have  EMG
> >>>>data of 24000 data points with a sampling frequeny of 800Hz (30
>seconds
>
> >>>>of continous data). I would like to do the  Timefrequency  analysis
>for
> >>>>this data and to see the power for  the whole 30 seconds
> >>>
> >>>use preprocessing to get the EMG data into a single 30s trial (if  you
> >>>want to analyze the rectified EMG, then do the rectification  in
> >>>preprocessing), then use frequanalysis with
> >>>
> >>>cfg.method = 'mtmfft';
> >>>cfg.output = 'pow';
> >>>
> >>>this should give you the power spectrum of your EMG data over the
> >>>entire 30 second period.
> >>>
> >>>Regards,
> >>>Christian
> >>>
> >>>
> >>>--------------------------------------------------------------------- -
> >>>Christian Hesse, PhD, MIEEE
> >>>
> >>>F.C. Donders Centre for Cognitive Neuroimaging
> >>>P.O. Box 9101
> >>>NL-6500 HB Nijmegen
> >>>The Netherlands
> >>>
> >>>Tel.: +31 (0)24 36 68293
> >>>Fax: +31 (0)24 36 10989
> >>>
> >>>Email: c.hesse at fcdonders.ru.nl
> >>>Web: www.fcdonders.ru.nl
> >>>--------------------------------------------------------------------- -
> >>>
> >>>
> >>>
> >>>
> >>
> >>_________________________________________________________________
> >>Tried the new MSN Messenger? It's cool! Download now. http://
> >>messenger.msn.com/Download/Default.aspx?mkt=en-in
> >>
> >
> >----------------------------------------------------------------------
> >Christian Hesse, PhD, MIEEE
> >
> >F.C. Donders Centre for Cognitive Neuroimaging
> >P.O. Box 9101
> >NL-6500 HB Nijmegen
> >The Netherlands
> >
> >Tel.: +31 (0)24 36 68293
> >Fax: +31 (0)24 36 10989
> >
> >Email: c.hesse at fcdonders.ru.nl
> >Web: www.fcdonders.ru.nl
> >----------------------------------------------------------------------
> >
> >
> >
> >
>
>_________________________________________________________________
>Get Married in 2007. Join Shaadi.com
>http://www.shaadi.com/ptnr.php?ptnr=mhottag

_________________________________________________________________
Crave for a healthier lifestyle? Ask an expert
http://content.msn.co.in/Lifestyle/AskExpert/Default07.htm